Turbomachinery, such as gas turbine engines, typically includes one or more rotatable assemblies with any number of rotatable blade rows. For example, certain aircraft gas turbine engines may include a fan for moving large volumes of air, thereby providing thrust. A typical fan structure includes a plurality of radially extending fan blades circumferentially offset from one another. Such fan blades may include a platform near the root portion thereof for defining the inner flow surface for air moving through the fan. In addition, the fan blades may be removably attached to a disk for ease of assembly and replacement of damaged blades.
A gap typically exists between adjacent blade platforms which may result in fan blade air loss therethrough if an appropriate seal is not provided. In the past, thin flexible seals between adjacent platforms have been occasionally used to seal these gaps. One side of the seal is attached to one of the blade platforms while the other side hangs loose under the gap so that when the fan starts to rotate, the seal is urged radially outwardly against the gap by centrifugal force, thereby providing an effective seal. For example, U.S. Pat. No. 4,183,720--Brantley, discloses such a seal.
While such seals may be generally effective, they may be unsatisfactory in certain applications. For example, certain fan blades, such as those which use a mid-span shroud, are removed from the disk by being dropped radially inwardly. This motion is necessary to disengage the mid-span shroud before further removing the blade. Similarly, other blading configurations exist which require radial motion of the blade during assembly and disassembly. Seals, such as those described above, interfere and restrict such blade motion and are generally unsuited for such applications.